CAIE P3 2015 June — Question 2 4 marks

Exam BoardCAIE
ModuleP3 (Pure Mathematics 3)
Year2015
SessionJune
Marks4
PaperDownload PDF ↗
Mark schemeDownload PDF ↗
TopicModulus function
TypeSolve |linear| compared to linear: algebraic only
DifficultyModerate -0.5 This is a straightforward modulus inequality requiring students to consider two cases (x ≥ 2 and x < 2) and solve linear inequalities in each case. While it requires understanding of the modulus function definition, the algebraic manipulation is simple and this is a standard textbook exercise with no novel insight required, making it slightly easier than average.
Spec1.02l Modulus function: notation, relations, equations and inequalities

2 Solve the inequality \(| x - 2 | > 2 x - 3\).

AnswerMarks Guidance
EITHER: State or imply non-modular inequality \((x-2)^2 > (2x-3)^2\), or corresponding equationB1
Solve a 3-term quadratic, as in Q1M1
Obtain critical value \(x = \frac{5}{3}\)A1
State final answer \(x < \frac{5}{3}\) onlyA1
OR1: State the relevant critical linear inequality \((2-x) > (2x-3)\), or corresponding equationB1
Solve inequality or equation for \(x\)M1
Obtain critical value \(x = \frac{5}{3}\)A1
State final answer \(x < \frac{5}{3}\) onlyA1
OR2: Make recognisable sketches of \(y = 2x-3\) and \(y =x-2 \) on a single diagram
Find x-coordinate of the intersectionM1
Obtain \(x = \frac{5}{3}\)A1
State final answer \(x < \frac{5}{3}\) onlyA1 4
**EITHER:** State or imply non-modular inequality $(x-2)^2 > (2x-3)^2$, or corresponding equation | B1 |

Solve a 3-term quadratic, as in Q1 | M1 |

Obtain critical value $x = \frac{5}{3}$ | A1 |

State final answer $x < \frac{5}{3}$ only | A1 |

**OR1:** State the relevant critical linear inequality $(2-x) > (2x-3)$, or corresponding equation | B1 |

Solve inequality or equation for $x$ | M1 |

Obtain critical value $x = \frac{5}{3}$ | A1 |

State final answer $x < \frac{5}{3}$ only | A1 |

**OR2:** Make recognisable sketches of $y = 2x-3$ and $y = |x-2|$ on a single diagram | B1 |

Find x-coordinate of the intersection | M1 |

Obtain $x = \frac{5}{3}$ | A1 |

State final answer $x < \frac{5}{3}$ only | A1 | 4 |
2 Solve the inequality $| x - 2 | > 2 x - 3$.

\hfill \mbox{\textit{CAIE P3 2015 Q2 [4]}}